Several chaos-based random bit generators have been proposed. Until now, systems, have theoretically been produced, which generate perfect random bit streams. However, the practical implementation is usually critical since often several constraints must be verified, e.g. over process variations, power supply, temperature, in order to keep the circuit in a chaotic evolution. Many problems are associated with designing a robust random bit generators based on a chaotic system, and many challenges stand in the way of producing a chaotic system which has none or minimal constraints to keep the system in a chaotic regime.